Advice needed on new social networking site

Firstly, thank you for providing this outlet for us to communicate, share information, and solve problems.
I am a novice when it comes to WP/WPMU/Buddypress. I am building a social networking site using the Buddypress Social Theme.
Let's say that this site has 1000 very active users. What advice would you give in order to make sure the site functions optimally? By optimally I mean no slowness issues, downtime, data loss, redundancy, etc. Should I use a shared hosting or a dedicated hosting? Any information/advice that you can provide will be appreciated.